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Audio bitrate too low

Posted: Mon Jan 11, 2021 11:54 pm
by rhb
I'm currently in the process of burning a number of old music videos (in mpeg2 format, converted and de-interlaced from VOB) to DVD. These videos all have their original audio tracks, which are in the PCM format at 1536 kb/s. Now, since these are native DVD audio tracks, I'd assumed they could be copied directly along with the video. I was wrong! Not only does ConvertX re-encode them (into AC 3), it does so at the very low bit rate of 192 kb/s. This is no good for my purposes, as the DVDs are being used to archive the videos - there's no point doing so if I'm going to be losing the original high-quality audio. So, am I just being dumb here? Is there a setting somewhere (other than 'copy when possible' which I've already selected) that would enable me to keep the original audio? Or, failing that, to specify a higher output bit rate that would minimise the quality loss?

Re: Audio bitrate too low

Posted: Tue Jan 12, 2021 6:01 am
by Coral
ConvertXtoDVD always converts to typical DVD standards.

This should explain: ... /DVD-Audio

Re: Audio bitrate too low

Posted: Tue Jan 12, 2021 2:14 pm
by rhb
Thanks very much for the quick response, and for the informative link. I'm still a little puzzled, though - the audio tracks I'm using are already DVD audio streams so should be fully compliant. Still, I could live with the format conversion if only I could keep the bitrate (or at least set it to higher than 192 kb/s, which is awfully low). ConvertXtoDVD is reducing the bitrate of the original audio by a whopping 87.5% so I'm unquestionably losing data (and quality) there.

As an afterthought, could I just replace the converted files in the VIDEO-TS folder that ConvertXtoDVD has created with the originals (renamed appropriately)?

Re: Audio bitrate too low

Posted: Tue Jan 12, 2021 3:52 pm
by rhb
This is growing more interesting. Having now played around with my original files, I'm not sure the original audio tracks are 1536 kb/s. They display as such in MediaInfo but when I transcode the source mpeg files into VOBs I seem to get a selection of different bitrate outputs. So, the 1536 kb/s may come from the mpeg container rather than the DVD source.

My new plan is to encode the original audio files as higher bitrate (640 kb/s) AC3 files to see if ConvertXtoDVD will then accept them as compliant and copy them. I may still try the file-replacement-in-the-VIDEO-TS-folder trick (since ConvertXtoDVD also significantly reduces the bitrate of the video) but that's an experiment for another day!